PyOTP Documentation. Release PyOTP contributors

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1 PyOTP Documentation Release PyOTP contributors Jun 10, 2017

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3 Contents 1 Quick overview of using One Time Passwords on your phone 3 2 Installation 5 3 Usage Time-based OTPs Counter-based OTPs Generating a base32 Secret Key Google Authenticator Compatible Working example Links API documentation 9 5 Table of Contents 13 Python Module Index 15 i

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5 PyOTP Documentation, Release PyOTP is a Python library for generating and verifying one-time passwords. It can be used to implement two-factor (2FA) or multi-factor (MFA) authentication methods in web applications and in other systems that require users to log in. Open MFA standards are defined in RFC 4226 (HOTP: An HMAC-Based One-Time Password Algorithm) and in RFC 6238 (TOTP: Time-Based One-Time Password Algorithm). PyOTP implements server-side support for both of these standards. Client-side support can be enabled by sending authentication codes to users over SMS or (HOTP) or, for TOTP, by instructing users to use Google Authenticator, Authy, or another compatible app. Users can set up auth tokens in their apps easily by using their phone camera to scan otpauth:// QR codes provided by PyOTP. We recommend that implementers read the OWASP Authentication Cheat Sheet and NIST SP : Digital Authentication Guideline for a high level overview of authentication best practices. Contents 1

6 PyOTP Documentation, Release Contents

7 CHAPTER 1 Quick overview of using One Time Passwords on your phone OTPs involve a shared secret, stored both on the phone and the server OTPs can be generated on a phone without internet connectivity OTPs should always be used as a second factor of authentication (if your phone is lost, you account is still secured with a password) Google Authenticator and other OTP client apps allow you to store multiple OTP secrets and provision those using a QR Code 3

8 PyOTP Documentation, Release Chapter 1. Quick overview of using One Time Passwords on your phone

9 CHAPTER 2 Installation pip install pyotp 5

10 PyOTP Documentation, Release Chapter 2. Installation

11 CHAPTER 3 Usage Time-based OTPs totp = pyotp.totp('base32secret3232') totp.now() # => # OTP verified for current time totp.verify(492039) # => True time.sleep(30) totp.verify(492039) # => False Counter-based OTPs hotp = pyotp.hotp('base32secret3232') hotp.at(0) # => hotp.at(1) # => hotp.at(1401) # => # OTP verified with a counter hotp.verify(316439, 1401) # => True hotp.verify(316439, 1402) # => False Generating a base32 Secret Key pyotp.random_base32() # returns a 16 character base32 secret. Compatible with Google Authenticator and other OTP apps 7

12 PyOTP Documentation, Release Google Authenticator Compatible PyOTP works with the Google Authenticator iphone and Android app, as well as other OTP apps like Authy. PyOTP includes the ability to generate provisioning URIs for use with the QR Code scanner built into these MFA client apps: issuer_name= "Secure App") >>> 'otpauth://totp/secure%20app:alice%40google.com?secret=jbswy3dpehpk3pxp& issuer=secure%20app' initial_ count=0, issuer_name="secure App") >>> 'otpauth://hotp/secure%20app:alice%40google.com?secret=jbswy3dpehpk3pxp& issuer=secure%20app&counter=0' This URL can then be rendered as a QR Code (for example, using which can then be scanned and added to the users list of OTP credentials. Working example Scan the following barcode with your phone s OTP app (e.g. Google Authenticator): Now run the following and compare the output: import pyotp totp = pyotp.totp("jbswy3dpehpk3pxp") print("current OTP:", totp.now()) Links Project home page (GitHub) Documentation (Read the Docs) Package distribution (PyPI) Change log RFC 4226: HOTP: An HMAC-Based One-Time Password RFC 6238: TOTP: Time-Based One-Time Password Algorithm ROTP - Original Ruby OTP library by Mark Percival OTPHP - PHP port of ROTP by Le Lag OWASP Authentication Cheat Sheet NIST SP : Digital Authentication Guideline 8 Chapter 3. Usage

13 CHAPTER 4 API documentation class pyotp.totp.totp(*args, **kwargs) Handler for time-based OTP counters. at(for_time, counter_offset=0) Accepts either a Unix timestamp integer or a datetime object. Parameters for_time (int or datetime) the time to generate an OTP for counter_offset the amount of ticks to add to the time counter Returns OTP value Return type str now() Generate the current time OTP Returns OTP value Return type str provisioning_uri(name, issuer_name=none) Returns the provisioning URI for the OTP. This can then be encoded in a QR Code and used to provision an OTP app like Google Authenticator. See also: Parameters name (str) name of the user account issuer_name the name of the OTP issuer; this will be the organization title of the OTP entry in Authenticator Returns provisioning URI Return type str 9

14 PyOTP Documentation, Release verify(otp, for_time=none, valid_window=0) Verifies the OTP passed in against the current time OTP. Parameters otp (str) the OTP to check against for_time (int or datetime) Time to check OTP at (defaults to now) valid_window (int) extends the validity to this many counter ticks before and after the current one Returns True if verification succeeded, False otherwise Return type bool class pyotp.hotp.hotp(s, digits=6, digest=<built-in function openssl_sha1>) Handler for HMAC-based OTP counters. at(count) Generates the OTP for the given count. Parameters count (int) the OTP HMAC counter Returns OTP Return type str provisioning_uri(name, initial_count=0, issuer_name=none) Returns the provisioning URI for the OTP. This can then be encoded in a QR Code and used to provision an OTP app like Google Authenticator. See also: Parameters name (str) name of the user account initial_count (int) starting HMAC counter value, defaults to 0 issuer_name the name of the OTP issuer; this will be the organization title of the OTP entry in Authenticator Returns provisioning URI Return type str verify(otp, counter) Verifies the OTP passed in against the current time OTP. Parameters otp (str) the OTP to check against count (int) the OTP HMAC counter pyotp.utils.build_uri(secret, name, initial_count=none, issuer_name=none, algorithm=none, digits=none, period=none) Returns the provisioning URI for the OTP; works for either TOTP or HOTP. This can then be encoded in a QR Code and used to provision the Google Authenticator app. For module-internal use. See also: Parameters 10 Chapter 4. API documentation

15 PyOTP Documentation, Release secret (str) the hotp/totp secret used to generate the URI name (str) name of the account initial_count (int) starting counter value, defaults to None. If none, the OTP type will be assumed as TOTP. issuer_name (str) the name of the OTP issuer; this will be the organization title of the OTP entry in Authenticator algorithm (str) the algorithm used in the OTP generation. digits (int) the length of the OTP generated code. period (int) the number of seconds the OTP generator is set to expire every code. Returns provisioning uri Return type str pyotp.utils.strings_equal(s1, s2) Timing-attack resistant string comparison. Normal comparison using == will short-circuit on the first mismatching character. This avoids that by scanning the whole string, though we still reveal to a timing attack whether the strings are the same length. 11

16 PyOTP Documentation, Release Chapter 4. API documentation

17 CHAPTER 5 Table of Contents genindex modindex search 13

18 PyOTP Documentation, Release Chapter 5. Table of Contents

19 Python Module Index p pyotp, 9 pyotp.hotp, 10 pyotp.totp, 9 pyotp.utils, 10 15

20 PyOTP Documentation, Release Python Module Index

21 Index A at() (pyotp.hotp.hotp method), 10 at() (pyotp.totp.totp method), 9 B build_uri() (in module pyotp.utils), 10 H HOTP (class in pyotp.hotp), 10 N now() (pyotp.totp.totp method), 9 P provisioning_uri() (pyotp.hotp.hotp method), 10 provisioning_uri() (pyotp.totp.totp method), 9 pyotp (module), 9 pyotp.hotp (module), 10 pyotp.totp (module), 9 pyotp.utils (module), 10 S strings_equal() (in module pyotp.utils), 11 T TOTP (class in pyotp.totp), 9 V verify() (pyotp.hotp.hotp method), 10 verify() (pyotp.totp.totp method), 9 17